(1) Field of the Invention
This invention relates to a lumped-constant type delay line made of an inductance element and capacitors, and more particularly to a subminiature ultra-high speed delay line possessing a very fast rise time and befitting digital circuits.
(2) Description of the Prior Art
Heretofore, delay lines having a fast rise time on the order of less than 1 ns, for example, which are made of coaxial cables cut to lengths appropriate for particular delay times desired have been preponderantly used.
The delay lines made of such coaxial cables are large and entail troublesome treatment as regards terminals. Further, they have no fixed size because their lengths vary with the length of delay time they are expected to generate. Thus, they pose some difficulty when they are to be laid out in conjunction with other semiconductor components in a printed circuit board for the production of an electronic apparatus.
Lumped-constant type delay lines combining an inductance element of the type having a conductor coiled on a bobbin and capacitors are also available. These lumped-constant type delay lines, however, have a disadvantage in that their inductance element assume a frequency characteristic when their frequency exceeds levels of around 1 GHz, for example, the inductance element are not easily coupled in optimum conditions, and their magnitudes of Q tend to decline so much as to impair their delay and amplitude characteristics. In these circumstances, it has been thought that these delay lines will not easily acquire good delay characteristics, especially ultra-high speed delay characteristics requiring a rise time of not more than 1 ns.